They say chess is the game of kings, and Radovid proved this point twice over during his meeting with Geralt. First, by playing the royal game at the Oxenfurt Chess Club while they met, and then by treating Geralt like a pawn he could send out to do his bidding. His requested move? Witcher takes sorceress: his spies had reported finding signs of Philippa Eilhart's presence in the elven ruins outside of Novigrad. Geralt was to go there and retrieve her. Normally Geralt resisted attempts to command him around the board, but he owed Radovid a favor - and had his own reasons for wanting to find Philippa...

Geralt found and searched Philippa's hideout. Though there were signs of her presence everywhere, the sorceress herself was long gone.

She had, however, left one thing behind that could prove of great value - a damaged crystal from her megascope. The witcher knew such a gem could, if properly probed, reveal priceless information about her doings. He thus was faced with a choice - should he give the crystal to Radovid, or take it to one of his sorceress allies?

If Geralt takes the crystal to Triss:

Geralt took the crystal to Triss. A bit of magic and she got it to play back a fragment from the last conversation Philippa had with Margarita Laux-Antille. From it they learned the sorceress, whom Radovid had blinded, was trying to restore her vision, and that both were planning to bring the Lodge of Sorceresses back to life.

The witcher decided it would be best if such information never made it to Radovid's ears. He thus decided to leave the crystal with Triss.

If Geralt takes the crystal to Yennefer:

Geralt took the crystal to Yennefer. A bit of magic and she got it to play back a fragment from the last conversation Philippa had with Margarita Laux-Antille. From it they learned the sorceress, whom Radovid had blinded, was trying to restore her vision, and that both were planning to bring the Lodge of Sorceresses back to life.

The witcher decided it would be best if such information never made it to Radovid's ears. He thus decided to leave the crystal with Yennefer.

If Geralt reports to Radovid promising only his word:

Out of a sense of duty, or perhaps a desire to receive at least part of the promised reward, Geralt returned to Radovid to tell him what he had found in Philippa's hideout. The king was clearly not pleased with the outcome of the investigation and dismissed the witcher. As for compensation for his trouble, sadly, the witcher had to go without...

Additionally, if Geralt gave the crystal to the witch hunters before:

Geralt encountered Radovid's men at the entrance to Philippa's hideout. They demanded the witcher give them the magic crystal, with assurances they would deliver it to the king personally. Geralt reluctantly accepted their offer.

If Geralt reports to Radovid with the megascope crystal:

As agreed, Geralt returned to Radovid and gave him the crystal from Philippa's megascope. Though the king was hoping to be handed a sorceress, not a cold, damaged lump of minerals, in the end he appreciated Geralt's effort and paid him his reward.

When you descend from the outside through the hole in the ground, before entering the hideout previously barred by a force field, use Aard on the cracked wall behind you. It will lead to a secret stash where you will find the Feline silver sword diagram for the Scavenger Hunt: Cat School Gear.

If you get the quest before finishing Yennefer's questline (main story) on Skellige, this quest will not show an option to give her the crystal. If you don't give it to Triss, it will appear that the only option is to give it to Radovid. But if you hold on to the crystal until you finish the main story on Skellige, you will get the option to give it to Yennefer.

If you wish to give the crystal to Triss, the mission must be completed before starting A Matter of Life and Death or before reading Triss' letter for the follow up quest Now or Never. You cannot talk to her about the crystal during either quest, except during the very first objective for Now or Never which requires you to read her letter.

Upon getting outside of the cave after picking the crystal, if you accept to give it away to the witch hunters (which arguably smells from the beginning), they will lie to Radovid and play the witcher for a fool. Geralt will then have nothing to justify himself when returning to the king, who will conclude that it's his words against the witch hunters' and that Geralt is not as reliable as he thought.